Don't panic if `close_tag()` is called without tags to close

This can happen when a tag is opened after the length limit is reached;
the tag will not end up being added to `unclosed_tags` because the queue
will never be flushed. So, now, if the `unclosed_tags` stack is empty,
`close_tag()` does nothing.

This change fixes a panic in the `limit_0` unit test.

0 files changed, 0 insertions, 0 deletions